The long range goal of my research is to determine how hormones regulate testicular development and differentiation. Spermatogenesis develops in an environment provided by the seminiferous tubule whose primary cell constituent is the Sertoli cell. the Leydig cell which produces androgens and potentially other hormonal factors, lies just outside the seminiferous tubule and is thought to act in a paracrine fashion on the cells of the seminiferous epithelium. In an effort to more clearly define sites of action, we remove the germinal epithelium which is about 80% of the total cell population and Leydig cells such that we may evaluate the requirement for products from Leydig cells. The absence of Leydig cells also permits studies of hormonal replacement to show potential positive effects on the seminiferous epithelium. The animal models we use are: (1) the in utero irradiated rat which is devoid of germinal epithelium and (2) the use of the drug ethane dimethane sulfonate which destroys Leydig cells. We use recombinant DNA technology to evaluate gene expression and many other molecular biology techniques to study changes in specific proteins produced. These studies will provide basic information related to hormonal control and regulation of spermatogenesis. Results from this work may have application in treatment of infertility and/or conversely in the prevention of fertility. Students currently work on various aspects of the problem and each student is given a particular area for study. Students receive training in molecular biology and related fields.